Microbes can be used to decrease the use of chemical fertilisers and pesticides.Explain how this can he accomplished.
Answers
Answer:
Explanation: The use of chemical fertilisers and pesticides to meet the ever increasing demand of
agricultural product has contributed significantly to environmental pollution, which is
a major cause of concern. We have now realised that there are problems associated
with the overuse of chemical fertilisers and there is a large pressure to switch to
organic farming the use of biofertilisers.
Biofertilisers are organisms that enrich the nutrient quality of the soil. The
main sources of biofertilisers are microbes (eg. Bacteria, fungi and cyanobacteria).
The nodules on the roots of legnminous plants formed by the symbiotic association of
Rhizobium, fix atmospheric nitrogen into organic forms, which is used by the plants
as nutrient. Other bacteria can fix atmospheric nitrogen while free-living in the soil
(eg. Azospirillum and Azobacter), thus enriching the nitrogen content of the soil.
Fungi are also known to form symbiotic associations with plants (mycorrhiza).
The fungal symbiont in these associations absorbs phosphorus from soil and passes it
to the plant. Plants having such associations show other benefits also, such as
resistance to root-borne pathogens, tolerance to salinity and drought and an overall
increase in plant growth and development.
Cyanobacteria are autotrophic microbes which can fix atmospheric nitrogen,
eg. Anabaena, Nostoc, Oscillatoria, etc. In Paddy fields, cyanobacteria serve as an
important biofertiliser. Blue green algae also add organic matter to the soil and
increase its fertility. Currently, in our country, a number of fertilisers are available
commercially in the market and farmers use these regularly in their fields to replenish
soil nutrients and to reduce dependence on chemical fertilisers.